A variety of substituted 2,6-dinitroaromatic compositions have been found to be extremely effective as pre-emergence herbicidal compositions. Many have been effective for controlling crab grass, pigweed, lambs quarters, wild oats, green foxtail, morning-glory and barnyard grass. Typically these compositions are prepared by chlorinating a substituted aromatic, then dinitrating the chlorinated 2,6-aromatic and displacing the labile chlorine atom with a primary or secondary amine to form the 2,6-dinitroaniline derivative. Representative compositions having pre-emergence herbicidal properties and methods for producing these compositions are shown in the following patents:
U.S. Pat. No. 3,920,742 discloses the preparation of N-sec-alkyl-2,6-dinitro-3,4 xylidine herbicide represented by the formula ##STR1## where R represents 1-ethylbutyl; 1-ethylpropyl; 1-methylpropyl, and 1-methylbutyl. The compositions are prepared by reacting the 1-chloro-2,6-dinitroaromatic, with an appropriately substituted primary or secondary amine at temperatures of from 50.degree.-150.degree. C. The compositions then are formulated into dust, dust concentrates, wettable powders, granulars, etc. for application to the soil that rates of about 1/8th to 20 pounds per acre of active material.
U.S. Pat. No. 4,025,538 discloses the preparation of 2,6-dinitroaniline compositions represented by the formula ##STR2## wherein
Y represents halogen, alkyl C.sub.1 -C.sub.4, alkenyl C.sub.2 -C.sub.4, CF.sub.3, CN or --SO.sub.2 NR.sub.3 R.sub.4 ;
Z represents alkyl C.sub.1 -C.sub.4 ; alkenyl C.sub.2 -C.sub.4 or mono-substituted alkyl C.sub.1 -C.sub.4 where the substituent is halogen, C.sub.1 -C.sub.4 alkoxy or --NR.sub.3 R.sub.4 ;
R.sub.1 represents hydrogen, C.sub.1 -C.sub.6 alkyl, C.sub.2 -C.sub.6 alkenyl or alkynyl C.sub.2 -C.sub.6 ;
R.sup.2 represents alkyl C.sub.1-7 (straight, branched or cyclic), alkenyl C.sub.2-6, alkynyl C.sub.2-6, or mono-substituted alkyl C.sub.1-4 where the substituent is halogen or alkyl C.sub.1-4 ; and
R.sub.3 and R.sub.4 each represent hydrogen or C.sub.1 -C.sub.4 alkyl and where R.sub.1 and R.sub.2 when taken together represent piperidino, pyrrolidino, or morpholino.
These compositions are prepared by reacting an appropriately substituted amine with the halogenated derivative.
U.S. Pat. No. 4,091,096 discloses a variety of dinitroanilines for the control of phytopathogens, such compositions being represented by the formula ##STR3## where R.sub.1 is hydrogen, C.sub.2 -C.sub.3 alkyl, chloroethyl, cyanoethyl, C.sub.3 -C.sub.4 alkenyl or halo, C.sub.3 -C.sub.4 alkenyl; and when R.sub.1 is H, R.sub.2 is N(R.sub.3).sub.2 C.sub.3 -C.sub.6 alkyl, branched C.sub.4 -C.sub.7 alkyl containing no tertiary carbon atoms, 1-hydroxy-2-propyl, methallyl, N-ethyl-3-piperidyl, 2,6-dimethyl-1 piperidyl and the like. These compositions like the others are prepared by the nucleophilic substitution of a halogen atom in the 1-position by an amine.
U.S. Pat. Nos. 4,101,582; 4,124,639 and 4,165,231 show further variations in terms of composition and the methods of preparing 2,6-dinitroaniline herbicides. A variety of substituents are shown on these particular compositions.